COMMON SAND-STAR. 



and fiddle-shaped. The disk of the largest specimen I 

 have taken was nine-tenths of an inch broad ; and the rays 

 vary from three times the length of the disk's breadth, or 

 even less, to five times as large. The disk is generally 

 reddish, marbled with purple-brown ; the sides white ; and 

 the under surface and spines are generally pale yellowish, 

 or white. 



Dr. Johnston records a remarkable variety or rather 

 monstrosity, having a square disk and four rays, the other 

 parts also regulated by the number four. I have the disk 

 of a young one presenting a somewhat similar appearance ; 

 but in it there are five arms, two of them originating 

 together, so that the quaternary arrangement of the other 

 parts may be looked upon as the result of the union of 

 two sets of organs. 



When very young, this species has much the aspect of 

 an Ophiocoma ; the lateral spines are longer in proportion 

 to the rays, and the latter are not so deeply inserted in 

 the disk. On comparing a series of specimens from a very 

 small size to the full grown state, we see that the chief 

 increase has been on the outer edge of the disk (the centre 

 being perfect in the arrangement of its scales in the young- 

 est specimen), and at the sides of the superior arm-plates, 

 which are at first almost ovate. 



The common Sand-star is found on most parts of the 

 British coast, and does not confine itself so much to sandy 

 ground as the next species. In England, Dr. Coldstream 

 found it in Devonshire, Mr. Couch in Cornwall, Pennant 

 in Anglesea ; and Mr. Bean says it is dredged in deep 

 Mater at Scarborough, but is very rare. Dr. Johnston 

 takes it at Berwick, and it is abundant near the mouth of 

 the Frith of Forth ; but is superseded by the next species, 

 higher up that estuary. On the Dogger Bank, and gene- 



